1// -*- C++ -*- Exception handling routines for Transactional Memory.
2// Copyright (C) 2009-2015 Free Software Foundation, Inc.
3//
4// This file is part of GCC.
5//
6// GCC is free software; you can redistribute it and/or modify
7// it under the terms of the GNU General Public License as published by
8// the Free Software Foundation; either version 3, or (at your option)
9// any later version.
10//
11// GCC is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15//
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25#include <cstdlib>
26#include "unwind-cxx.h"
27
28using namespace __cxxabiv1;
29
30// Free one C++ exception.
31
32static void
33free_any_cxa_exception (_Unwind_Exception *eo)
34{
35  __cxa_refcounted_exception *h
36    = __get_refcounted_exception_header_from_ue (eo);
37
38  if (__is_dependent_exception (eo->exception_class))
39    {
40      __cxa_dependent_exception *dep
41	= __get_dependent_exception_from_ue (eo);
42
43      h = __get_refcounted_exception_header_from_obj (dep->primaryException);
44
45      __cxa_free_dependent_exception (dep);
46    }
47
48#if __GCC_ATOMIC_INT_LOCK_FREE > 1
49  if (__atomic_sub_fetch (&h->referenceCount, 1, __ATOMIC_ACQ_REL) == 0)
50#endif
51    __cxa_free_exception (h + 1);
52}
53
54// Cleanup exception handling state while rolling back state for
55// a software transactional memory transaction.
56//
57// UNTHROWN_OBJ is non-null if we've called __cxa_allocate_exception
58// but not yet called __cxa_throw for it.
59//
60// CLEANUP_EXC is non-null if we're currently processing a cleanup
61// along an exception path, but we've not caught the exception yet.
62//
63// CAUGHT_COUNT is the nesting depth of __cxa_begin_catch within
64// the transaction; undo as if calling __cxa_end_catch that many times.
65
66extern "C" void
67__cxxabiv1::__cxa_tm_cleanup (void *unthrown_obj,
68			      void *cleanup_exc,
69			      unsigned int caught_count) throw()
70{
71  __cxa_eh_globals *globals = __cxa_get_globals_fast ();
72
73  // Handle a C++ exception not yet thrown.
74  if (unthrown_obj)
75    {
76      globals->uncaughtExceptions -= 1;
77      __cxa_free_exception (unthrown_obj);
78    }
79
80  // Handle an exception not yet caught ie. processing a cleanup
81  // in between the throw and the catch.
82  if (cleanup_exc)
83    {
84      _Unwind_Exception *eo
85	= reinterpret_cast <_Unwind_Exception *>(cleanup_exc);
86      if (__is_gxx_exception_class (eo->exception_class))
87	free_any_cxa_exception (eo);
88      else
89	_Unwind_DeleteException (eo);
90    }
91
92  // Do __cxa_end_catch caught_count times, but don't bother running
93  // the destructors for the objects involved.  All of that is being
94  // undone by the transaction restart.
95  if (caught_count > 0)
96    {
97      __cxa_exception *h = globals->caughtExceptions;
98
99      // Rethrown foreign exceptions are removed from the stack immediately.
100      // We would have freed this exception via THIS_EXC above.
101      if (h == NULL)
102	return;
103
104      do
105	{
106	  __cxa_exception *next;
107	  _Unwind_Exception *eo = &h->unwindHeader;
108
109	  if (__is_gxx_exception_class (eo->exception_class))
110	    {
111	      next = h->nextException;
112	      free_any_cxa_exception (eo);
113	    }
114	  else
115	    {
116	      _Unwind_DeleteException (eo);
117	      next = 0;
118	    }
119
120	  h = next;
121	}
122      while (--caught_count);
123
124      globals->caughtExceptions = h;
125    }
126}
127